1. Field of the Invention
This invention relates generally to computers, and more specifically to computers that display multiple windows at differing resolutions.
2. Related Art
Conventionally, computers are equipped with CRT-type monitors of a predetermined resolution (e.g., 1120.times.750 dots) and performed display by means of a CRT controller and a video memory having a capacity corresponding to this resolution.
Some computers execute a single application under the control of a single operating system, while other computers execute multiple applications under a single operating system. Further, configurations are possible in which one of the multiple application programs is executed under the control of a minor operating system being executed as a subordinate process of the main operating system. Therefore, there is a need to be able to display a window of one program at a resolution that matches the resolution of the CRT, i.e., 1120.times.750 dots, and to display a window of another program at a resolution different born that resolution (e.g., 640.times.400 dots).
The former is referred to as "high-resolution mode" screen display, and the latter is referred to as "normal mode" screen display. Conventional computer display systems that satisfy this need for both screen displays are configured such that the CRT is a multi-scan device that switches the deflection frequency, and the initial power-up condition is determined by a high resolution/normal selection switch provided on the computer.
However, when a window is displayed by an application program with a resolution different from that of the screen being displayed by another application, conventional computer display systems require much time and trouble in switching. This is because when switching, the series of actions of terminating the first application program, turning the power to the computer display system off, switching the selection switch, turning on the power to the computer display system and executing the next application program must be performed in sequence.
There are conventional computer systems with displays in which a number of windows are open on the screen and processing by each of the application programs is assigned to each window. When one of the open windows is selected, the selected window is displayed on the very top layer and the process assigned to that window is active.
Further, when multiple windows are open on some of these computers, the size of the selected window can be increased to enlarge the display area by means of a mouse or other pointing device or the combination of prescribed keys referred to as hot keys.
However, when the maximum resolution that can be handled by the program controlling the window is smaller than the resolution of the full size of the screen in computers with this window system, the display area of the window is only part of the screen even when the window is at its maximum size and the window cannot be displayed over the entire screen. In the case of an application program having maximum resolution of 640.times.400 dots, that application can only be opened in a window that occupies part of the screen (approximately one third of display area) when run on a computer with a screen having a resolution of 1120.times.750 dots.
The present invention solves this problem, and facilitates the rapid switching of display of multiple screens with differing resolutions and in particular to facilitate the rapid switching of display between windows when those screens are displayed in windows.